Pleased as punch with your new Lexus GS 430, you spot the mile marker ahead where the speed limit jumps from 35 to 70 mph. This will be fun, and now another GS is alongside. The limit leaps, you both nail it and with surprising ease he leaves you behind.

That would be the hybrid GS 450h.

Lexus has shifted the hybrid automobile out of the slow-lane, NPR-listening, bless-'em-for-their-dedication people who buy hybrids to save the world. We applaud those drivers, but this is a new animal.

Lexus opened the hybrid-as-fun door a bit with the RX 400h SUV, but kicks it wide with the GS 450h. Get this: Lexus claims the GS hybrid scoots to 60 mph in 5.2 seconds, an equal to 60—by our clocks—with the BMW 545i, Dodge Magnum SRT8 and Mercedes-Benz CLK500. Hence the GS 450h's unique nomenclature; its performance corresponds roughly to be that of a 4.5-liter V-8. Top speed for the gas/electric Lexus is said to be 131 mph. Fuel economy? City, highway and combined all in the 27–28 mpg level—what you'd expect from a frugal V-6 sedan.

Externally the GS 450h doesn't look so different, just little "hybrid" labels on the trunk and rocker panels plus distinctive 18-in. wheels. Inside, a power meter replaces the tachometer, and much of the GS 430 option list—short of the nav system and Mark Levinson sound system—is standard in the (we're guessing) $52,999 GS 450h.

Much of the drivetrain is similar to that in the RX 400h hybrid SUV, but with important differences. The engine for the GS is still a V-6, but a 3.5-liter 292-bhp, 267 lb.-ft. of torque Otto-cycle version similar to that in the IS 350 with two fuel injectors per cylinder, one direct, one in the port. Their purpose? To provide good power at both low and high speeds. There are still twin variable-timing camshafts per head and the intake timing is new to smooth transitions when the gasoline engine kicks in with the electric motors.

Because the GS is a "normal" car hybrid, it needed a transmission with about the same dimensions as those of the gasoline GS models, so Lexus developed the world's first longitudinal electronic CVT.

Other elements of this next-generation hybrid are smaller and more compact than in previous hybrids, like the voltage-converting inverter or the pack of 40 nickel/metal hydride batteries cocooned between back seat and trunk. A product of golf-loving Lexus, the GS 450h retains room for two golf bags in back.

As in other Toyota/Lexus hybrids, there are two electric motors: MG1 and MG2. MG1 functions as the generator and starter. MG2, rated at 197 bhp and 203 lb.-ft. of torque, is the motor that provides propulsion, silently launching the GS 450h under normal acceleration and adding supplementary power akin to a silent supercharger at higher speeds. New to the GS 450h is a Ravigneaux gearset which uses its planetary arrays in a manner immediately obvious to automatic transmission experts but a bit mysterious to everyone else. What you should care about is that it offers two speed ranges for the electric power.

Like any true hybrid, the GS 450h can drive away using silent electric power. Plant the throttle and the car's gasoline and electric personalities are combined, very quick but lacking the satisfying guttural V-8 sounds we expect. This isn't bad, just different.

In reality, that oomph-from-zero feeling isn't the best part of the GS 450h. It would be impossible to deal with the torque from the electric/gasoline power systems available from rest, so it is limited accordingly off the line. But get to about 20 mph, nail the throttle and prepare to be impressed. Because of the electronic CVT there is "motorboating," the V-6 shooting up in revs, hanging there and not sounding all that satisfying. But just watch the speedometer needle as it cranks to the right. And, my goodness, is it quiet.

Speed aside, this is not a hot-rodder's car, but more the sedan of aggressive golfers, with room for clubs, plenty of cossetting quiet and luxury, plus stylish good looks. Explaining the premium cost over a GS 430 in terms of saving fuel would be impossible, but there's nothing wrong with driving a techno-wonder. And if you do your bit to save the world, what's wrong with that?